[mem]: Fix handling of default resize to check alignment

core/mem/mem.odin

@@ -456,6 +456,17 @@ is_power_of_two :: proc "contextless" (x: uintptr) -> bool {
 	return (x & (x-1)) == 0
 }
 
+/*
+Check if a pointer is aligned.
+
+This procedure checks whether a pointer `x` is aligned to a boundary specified
+by `align`, and returns `true` if the pointer is aligned, and false otherwise.
+*/
+is_aligned :: proc "contextless" (x: rawptr, align: int) -> bool {
+	p := uintptr(x)
+	return (p & (1<<uintptr(align) - 1)) == 0
+}
+
 /*
 Align uintptr forward.